Jad Abumrad and Robert Krulwich have a new episode of Radiolab airing this week. The theme of the show is heredity and its attendant mysteries. I had great fun telling the strange and tragic story of the early twentieth century biologist Paul Kammerer, who thought he could change the human race with the help of a midwife toad. (Some of my favorite sources about this tale and its present-day reverberations are here, here, here, here, here, and here.)